[PATCH] Staging: setup.c : boot loader kernel arguments are secured over cmdline.txt arguments for some systems

[Kishore Karanala <kishore.karanala@gmail.com>]

boot loader kernel arguments are secured over cmdline.txt
arguments for some systems

Signed-off-by: Kishore Karanala <kishore.karanala@gmail.com>
---
 arch/x86/Kconfig        | 3 +++
 arch/x86/kernel/setup.c | 7 ++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e487493..3077fb0 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2224,6 +2224,9 @@ config CMDLINE
 	  In most cases, the command line (whether built-in or provided
 	  by the boot loader) should specify the device for the root
 	  file system.
+	 In some of the systems boot loader arguments needs dominated over
+	 cmdline arguments in systems like automotive , this can be done using
+	 CMDLINE="!root=/dev/mmcblk0p1 ro"
 
 config CMDLINE_OVERRIDE
 	bool "Built-in command line overrides boot loader arguments"
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 4cfba94..5fa3194 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -962,11 +962,16 @@ void __init setup_arch(char **cmdline_p)
 #ifdef CONFIG_CMDLINE_OVERRIDE
 	strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
 #else
-	if (builtin_cmdline[0]) {
+	if (builtin_cmdline[0] != '!') {
 		/* append boot loader cmdline to builtin */
 		strlcat(builtin_cmdline, " ", COMMAND_LINE_SIZE);
 		strlcat(builtin_cmdline, boot_command_line, COMMAND_LINE_SIZE);
 		strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
+	} else {
+		/* This will provide additional secuirty to cmdline */
+		/* arguments not overriding bootloader arguments */
+		strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
+		strlcat(boot_command_line, &builtin_cmdline[1], COMMAND_LINE_SIZE);
 	}
 #endif
 #endif
-- 
2.7.4